Experimental tests were conducted in the present study to investigate synthesis of aluminum ammonium sulfate (aluminum alum) by crystallization from the waste acid solution of aluminum surface finishing industry. Effects of various operating conditions including the molar ratio of ammonia and al...
South African coal fly ash represents an untapped secondary resource of aluminium. Continuous research is conducted to develop suitable chemical and/or geometallurgical processes for aluminium extraction, preferably accompanied by minimal silicon extraction. The thermochemical treatment of a Sou...
Ammonium aluminum sulphate was introduced to modify alumina bubbles by the wet chemical method. Distribution of ammonium aluminum sulphate, in situ decomposition characteristics, microstructure and mechanical properties of the modified alumina bubbles were investigated by SEM, XRD, BET and by a ...
The leaching efficiency (LE) of ion adsorption rare earth (IARE) by the sulfate and chloride of ammonium, magnesium and aluminum were comparatively determined using column leaching method. It is found that at equal equivalent concentration of cation, the LE of IARE by aluminum sulfate is the hig...
We recently showed that the selective extraction of aluminium from the amorphous phase of a South African ultrafine coal fly ash can be achieved via thermochemical treatment with ammonium sulphate for 1 h followed by aqueous dissolution, as an alternative to conventional hydrometallurgical proce...
The uniformity particle size distribution (PSD) and coarse particle size of alumina were synthesized by precipitating aluminum ammonium sulfate solution with ammonia. The effect of temperature and ammonia concentration on precipitation products was studied by using X-ray diffraction (XRD), field...
Tris-copper centers are present at the active site of multicopper oxidases (MCO) which couple the four-electron reduction of molecular oxygen to water with the oxidation of substrates. Modelling these sites with small molecular complexes has thus attracted the interest of many groups in the (bio...
New copper(I) complexes of the type [(PBz3)L3Cu]X, (PBz3)L2CuX, [(PBz3)2L2Cu]X, [(PBz3)3LCu]X (L=monodentate N-donor imidazole- or pyrazole-type ligand, Bz=benzyl, X=NO3 or ClO4), (PBz3)y(N-N)xCuNO3 (N-N=bis(pyrazol-1-yl)methane, x=y=1; N-N=bis(1,2,4-triazol-1-yl)methane, x=y=2), (PPh3)L2′CuX, ...
Polymers based on N-phenyl maleimide, N-4-propargyl methoxy phenyl maleimide and methyl methacrylate was synthesized. High glass temperatures 183, 179, 159 °C respectively for P1, P2 and P3 were achieved. EO polymer P3–C1, P3–C2 and P3–C3 with about 30 wt% chromophore loading density were pr...
Copper(I) catalyzed azide-alkyne cycloadditions, click reactions, are an established synthetic tool to derivatize polymers. Only a few catalytic systems have been explored towards the derivatization of functionalized poly(3‑hydroxyalkanoate)s, PHAs, using click reactions. Here, the performances ...
Artificial neural networks (ANNs) are used as an aid in developing force field parameters for modelling, using molecular mechanics methods and the MM2 force field, the porphyrins of the early transition metals, Sc(III), Ti(II), Ti(III), Ti(IV), V(II), V(III), V(IV), Cr(III), Cr(IV) and Cr(V), in...
The nature of the vanadium compounds in some petroleum crudes is reviewed. Oxovanadium(IV) phthalocyanine and oxovanadium(IV) Schiff base complexes are proposed as models of vanadium coordination in porphyrins and asphaltenes. Reactions of these compounds with hydrogen sulphide, thiols and other...
The distribution of vanadium and vanadyl porphyrins in fractions (extractable organic, inorganic and kerogen) of the Serpiano marl and the La Luna shaly limestone has been determined by employing a variety of geochemical and spectroscopic techniques including atomic absorption, atomic emission, ...
Spectroscopic analysis by Raman, diffuse reflectance spectroscopy and electron spin resonance of adsorbed oxovanadium(IV) porphyrins is reviewed. Two forms of donor-acceptor interactions are identified, namely coordination of the vanadyl group to eitner basic or acidic surface sites. In both cas...
Publisher SummaryThis chapter focusses on the properties of the novel vanadium-containing bromoperoxidases. Vanadium has been shown to be an essential requirement in the biological systems and the chemistry of the element is gaining considerable interest. As the chemistry of vanadium is of direc...
Vibrational mode assignments are made for most of the observed IR bands for the iron(III) complexes of the four classical isomers of etioporphyrin, octaethylporphyrin, 13-desethyletioporphyrin, and deuteroetioporphyrin by comparison with the IR spectra of the corresponding nickel complexes. The ...
A study has been initiated which utilizes the sensitivity and selectivity of resonance Raman (RR) scattering to establish vibrational “structure-marker” frequencies for petroporphyrins in crude oils and tar balls as an empirical tool in the determination and differentiation of numerous porphyr...
Reaction kinetics and mechanisms of the decomposition of vanadyl etioporphyrin (VO-EP), the most common metal compounds present in heavy crude, were studied in a mixed solvent of supercritical water (SCW) and toluene without the addition of any catalyst, H2 or H2S to remove vanadium. The aim of ...
A dipotassium pentacalcium dicalcein salt (“Statocalcein”) is recommended for use in place of Calcein as an indicator for fluorimetric titration of calcium with EDTA. The new indicator remains stable in solution for long periods (at least 210 days).
Different-sized α-calcium sulphate hemihydrate (α-CSH) rods were hydrothermally prepared by converting calcium sulphate dihydrate at 110–140 °C in the presence of MgCl2, sodium citrate (CANa), and sodium dodecyl benzene sulfonate (SDBS) as the modifiers. The α-CSH rods with the average diam...
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